1. Field of the Invention
This invention relates to a ratchet wrench, particularly to one facilitating to alter a rotation direction of a driving gear by change-over of an orientating member, able to achieve excellent efficacy of engagement and braking of the driving gear. In addition, it can stabilize transmission when the ratchet wrench works.
2. Description of the Prior Art
Generally, a ratchet wrench cooperating with different sleeves is employed for locking and detaching different kinds of bolts or nuts. A conventional ratchet wrench 1, as shown in FIG. 1, includes a main body 10 formed with an accommodating groove 100 and a receiving groove 101, the accommodating groove 100 bored with a through hole 102, and the receiving groove 101 provided with a control grip hole 103 and having a wall surface disposed with a recessed hole 104. A ratchet 11 is received in the accommodating groove 100, and an adjusting block 12 is set in the receiving groove 101 of the main body 10, with the ratchet teeth 110 of the ratchet 11 meshed with the teeth 120 at one side of the adjusting block 12. The ratchet 11 is mounted thereon with a sleeve engaging post 111 while the adjusting block 12 has an intermediate portion of another side provided with a projection 121 having two sides respectively formed with a concave arcuate surface 122. The recessed hole 104 of the main body 10 is fixed therein with a positioning ball 13 and a spring 14, the positioning ball 13 resisting against one of the two concave arcuate surfaces 122. A control grip 15 is positioned at an outer side of the main body 10 and connected with the adjusting block 12 by a shaft rod 16, and a blocking plate 17 to be covered and secured on the main body 10 by fixing members 18 is bored with a through hole 170 for the sleeve engaging post 111 of the ratchet 11 to be inserted therethrough and a shaft hole 171 for receiving the shaft rod 16 therein. Thus, when the control grip 15 is operated to actuate the adjusting block 12 to rotate and have one end transferred to closely lean on one sidewall of the receiving groove of the main body 10, the ratchet 11 will be held and braked by the adjusting block 12 to carry out one-way gearing.
However, the engagement of the ratchet 11 of the conventional ratchet wrench 1 with the teeth 120 of the adjusting block 12 is point contact or line contact; therefore, the ratchet 11 and the teeth 120 of the adjusting block 12 cannot stably carry out meshing transmission, likely to produce tooth skipping and indefinite gearing. In addition, when the adjusting block 12 is actuated to carry out braking to the ratchet 11, it is only by mutual resisting and engagement of the wall surfaces of the adjusting block 12 and of the receiving groove 101, which are smooth surfaces unable to produce great frictional force, thus failing to attain good effect of engagement and braking and also apt to slip off.